In situatomic-scale observation of the conversion behavior in a Cu-Zn alloy for twinnability enhancement

Cu-Zn based alloys have been widely used in various applications due to their outstanding properties, such as high electrical conductivity and increased hardness over pure Cu. The thermal effect during electrical conduction leads to the requirement of excellent thermal stability for maintaining performance, which is strongly related to the microstructural transformation and kinetics. However, the atomic-scale microstructural evolution of Cu-Zn systems has scarcely been discussed. In this study, the reaction process of Cu-Zn systems was observed via in situ high-resolution transmission electron microscopy (in situ HRTEM). The Zn/Cu thin films were converted to 13-CuZn at 180 degrees C and exhibited an epitaxial relationship with Cu, which was described as (01 1)13-CuZn // (111)Cu and [10 0]13-CuZn // [11 0]Cu. Subsequently, the Cu-rich solid solution (alpha phase) was formed at 300 degrees C to decrease the Gibbs free energy, where layer-by-layer diffusion took place on the (11 1) plane. Based on the improved twinnability of the alpha phase with decreasing stacking fault energy (SFE), nanotwins grew along with the alpha phase. The twin boundaries effectively retard atomic migration, which is expected to optimize the mechanical properties. The fundamental science described in this study provides novel insights into Cu-Zn alloys, which could be explored in a wide range of alloy systems.

Automated summary

Cu-Zn based alloys are widely used for their excellent properties, such as high electrical conductivity and increased hardness over pure Cu. This study investigates the atomic-scale microstructural evolution of Cu-Zn systems, revealing the formation of alpha phase and nanotwins to optimize mechanical properties. The research provides novel insights into Cu-Zn alloys for potential applications in various alloy systems.